class_docstr: Run tests for azfs backend using account key authentication.
code: def setUp(self):
      super().setUp()
  
      os.environ["TF_AZURE_USE_DEV_STORAGE"] = "1"
  
imports: import os
  import subprocess
  import sys
  import pytest
  import tensorflow
  import tensorflow_io
label_desc: Use image node_id 2 for calling the AZFSTest obj's underlying member method code with example usage: obj.setUp() without return types